Copper-base alloys



Feb. 26, 1963 A. w. o. WEBB ETAL 3,079

COPPER-BASE ALLOYS Filed Jan. 9, 1961 2 Sheets-Sheet 1 Manganese.

F l G l ttes This invention concerns improvements relating to copper-base alloys containing manganese, aluminium and iron, and also nickel and/ or tin.

In the specification of United States Patent No. 2,715,- 577 we disclosed an alloy containing to of manganese, 6.5 to 9% of aluminium, 2 to 4% of iron and 1.5 to 6% of nickel, and in the specification of United Kingdom Patent No. 809,973, a modification of that alloy in which the aluminium content is less than 6.5%, but not less than 3.5%. These alloys have good casting and welding characteristics, as well as good mechanical properties.

It has now been found that good mechanical properties can be obtained using contents of manganese in excess of 15%, provided that manganese of high purity is employed, and that outstandingly good properties can be obtained within a comparatively narrow range of composition hereinafter referred to.

A copper-base alloy in accordance with the present invention has a basically duplex character, consisting mainly of an alpha phase and a beta phase, and consists essentially of appreciably more than 15% and up to 35% of high-purity manganese, 3.5 to 9.5% of aluminium, 2 to 4% of iron, not more than 6% of nickel and/ or not more than 2% of tin, the minimum content of nickel being 1% when no tin is present and the minimum content of tin when no nickel is present being 0.25% while the minimum total of the nickel content plus four times the tin content is not less than 1% when both are present, and the aluminium equivalent (as hereinafter defined) of the aluminium and the manganese present lying within the range 9 to 12%. For most purposes, the manganese content will be not more than the aluminium content not more than 9% and the aluminium equivalent not more than 11.5%.

Alloys having a very good combination of properties for the production of castings such as marine propellers will have an aluminium equivalent of about 10%.

The effect of variation in manganese content on the structure and properties of the alloy is cnosiderably less than that of variation in aluminium content, but is pro portional over the Whole range of alloy compositions considered. It is possible therefore to give to manganese an aluminium-equivalent value similar to the zinc-equivalent values recognized by metallurgists practising with hightensile brasses. We have found that the aluminium-equivalent value of manganese in these copper-manganesealuminium alloys is 0.16 and this value is to be assumed as the basis for the aluminium equivalents referred to in this specification. The aluminium equivalent of the aluminium and manganese is the sum of the actual percentage of aluminium present plus the aluminium equivalent of the manganese present.

To obtain the most useful mechanical properties for marine-propeller manufacture, it is necessary to maintain a substantially constant alpha/ beta ratio in the alloy (about 55%60% alpha), which can be achieved by reducing the aluminium content as the manganese content is raised.

An alloy of this type containing 15.58% manganese and 7.46% aluminium (aluminium equivalent 9.95%) had a fatigue limit in air of 116.5 tons/sq. in. and a 3,079,252 Patented Feb. 26, 1963 "ice corrosion fatigue limit in sea water, based on 100,000,000 stress reversals, of :8.7 tons/ sq. in. This alloy has also been shown to have a very high resistance to corrosion of the impingement type.

For the necessary purity of the alloy, use will be made of high-purity manganese, for example electrolytic manganese, and subsequent contamination will be avoided. Contamination with carbon is particularly to be avoided. Small amounts of carbon in excess of 0.01%, have a marked influence on the tensile properties of the alloy, as is indicated by the following table:

Aluminium Carbon, 015% Proof Tensile Elongation, Equivalent, percent Stress tons/ Strength, percent percent sq. m. tons/sq. m.

manganese). The properties of three typical examples of alloys are as follows:

Alloy 1 Alloy 2 Alloy 3 Manganese, percent 15.6 20.1 35. 0 Aluminium, percent 7.6 6. 7 5. 0 Aluminium equivalent, percent 10.1 9. 9 10. 0 0.15% Proof Stress (tons/sq. in.) 23. 3 23. 3 22. 8 Tensile Strength (tons/sq. in.) 49. 8 47. 5 43. 2 Elongation, percent 24 25 27 Brinell Hardness No. (10/1000) 185 193 166 Alloys intended for castings other than marine propellers may require to have different combinations of properties, some requiring to be harder and stronger and others more ductile. Referring to the diagram shown in FIGURE 2 of the accompanying drawings, alloys having the composition limits indicated by the parallelogram g, lying on both sides of a line AB (indicating alloys with an aluminium equivalent of 10), have properties of considerable use for various purposes in the engineering industry. By way of examples, the proper-ties of two alloys, one of high strength and the other of great ductility are given below:

Alloy4 Alloyfi Manganese, percent 19. 7 15. 9 Aluminium, percent 7. 6 6. 7 Aluminium equivalent, percent 10.8 9. 3 0.15% Proof Stress (tons/sq. in.) 32. 8 18. 8 Tensile Strength (tons/sq. in) 53. 7 41. 8 Elongation, percent 12% 38 Brinell Hardness No. (101100 218 content, while -still maintaining high ductility, as the a31- lowing tableshows:

Manganese, Tin, 0.15% Proof Tensile Elongation, percent percent I Stress, Strength, percent tons/sq.'in. tons/sq. 111.

I1. 8 18.5 44. 4 35 11. 8 0. 46 18. 3 A3. 5 26 11.8 0. 02 18. 5 35.8 14 15.16 0 4 46:9 28 15.13 1. 04 24: 6 47. .0 26 -15.1; ,1. 5,6 23. 9 7 4e. 5 25 '15. 6 2.08 27, 1 13.8 -13 "0.15% Proof Tensile Elongaj Stress, Strength, tion,

=t0ns/sq.-'in. tons/sq.in..- percent as forged; 30:; 157.1 11 Forged and heat-treated- ,34. 8 i 56.6 16

' .We claim:

' 1. A'copper-base alloy having a basically duplex 'cha'ra'c'ter, consisting mainly of an alpha phase and a beta phase and consisting essentially of m'ore than 15 and up to 35% manganese, 3.5 to 9.5% of aluminium, 2

to 4% of iron, and 1 to 6% -of nickel, the aluminiume'quivalent of the aluminium and the manganese present lying within the range "9 to 12% where the aluminium- ;equivalent of manganese-is 0.16, and having a carbon :contentas an impurityjofles's than 0.02%. i

.2. An alloy according to claim 1 wherein the man- .ganese content is not. more than 20%, the aluminium content not more than'9% and the aluminium equivalent not more than 11.5%.

3. An alloy accordingto claim 1 for the production of castings such as marine propellers, wherein the aluminequivalent is about 5. A copper-base alloy havinga basically duplex character, consisting mainly of an alpha phase and a beta phase and consisting essentially of more than 15% and up to 35% of manganese, 3.5 to 9.5% of aluminium, 2 to 4% of iron and 0.25% to 2% of tin, the aluminiumequivalent of the aluminium and the manganese present lying within the range 9 to 12% when the manganeseequivalent of aluminium is 0.16, and having a carbon content as an impurity of less than 0.02%.

6. An alloy according to claim 5, wherein the manganese content is not more than the aluminium contentnot more than 9% "and the aluminium equivalent not more than 11.5%.

4; alloy according to claim 1,. wherein the aluminhim and manganese contents lie within the limits 7.6%

aluminium and 15% manganese on the one hand and 414% aluminium and 35% manganese on the other hand.

7. An alloy according to claim 5 for the production of castings such as marine propellers, wherein the aluminium equivalent is about 10%.

8. An alloy according to claim 5, wherein the aluminium and manganese contents lie within the limits 7.6% aluminium and 15% manganese on the one hand and 4.4% aluminium and 35% manganese on the other hand.

'9. Acopper-base alloy having a basically duplex character consisting'mainly of an alpha phase and a beta phase and consisting essentiallyof more than 15% and up to =35-% -of high-purity manganese, 3.5 to 9.5% of aluminium 2m 4% of iron, and at least one element of the group consisting of nickel and tin, the amount of nickel being not more than 6% and the amount of tin being not more than 2%, the minimum total of the nickel content plus four times, the tin content being at least 1%, and the aluminium-equivalent of the aluminium and the manganese present lying within the range from 9 to 12% where the aluminium-equivalent of manganese is 0.16, and having a carbon content as an impurity of less than 0.02%.

"10. An alloy according to claim 9, wherein the mangan'esecontent is not more than 20%, the aluminium content not more than 9% and the aluminium equivalent not more than 11.5%.

11. An alloy according to claim 9 for the production of castings such as marine propellers, wherein the aluminiumequivalent is about 10%.

12. .An alloy according to claim 9, wherein aluminium and manganese contents lie within the limits 7.6% aluminium and 15% manganese on the one hand and 4.4% aluminium and 35% manganese on the other hand.

-13. An alloy according to claim 9, wherein the proportion of the alpha phase is about -60% of the alloy.

Re ferences Cited in the file of this patent UNITED STATES PATENTS 2,715,577 Payne et a1 Aug. 16, 1955 

1. A COPPER-BASE ALLOY HAVING A BASICALLY DEPLEX CHARACTER, COMSISTING MAINLY OF AN ALPHA PAHSE AND A BETA PHASE AND CONSISTING ESSENTIALLY OF MORE THAN 15% AND UP TO 35% MAGNGANESE, 3.5 TO 9.5% OF ALUMINIUM, 2 TO 4% OF IRON, AND 1 TO 6% OF NICKEL, THE ALUMINIUMEQUIVALENT OF THE ALUMINUM AND THE MANGANESE PRESENT LYING WITHIN THE RANGE 9 TO 12% WHERE THE ALUMINUMEQUIVALENT OF MANGANESE IS 0.16, AND HAVING A CARBON CONTENT AS AN IMPURITY OF LESS THAN 0.02%. 